In reply to Milan Petrovic.

This is a simplistic view. Cost of human work is usually higher than anything else. Upgrading old systems to php 7 will require also upgrade of the dependencies, test etc. What is the gain you get if you already have a fully populated server that works well with lets say 5.2? There is a gain in supporting as little configuration options as you can as it minimizes the training and support knowledge required, adding new platform to support probably costs a lot, and the cost is actually relatively higher for the small players which is why they are getting extinct.